1. Field
Exemplary embodiments relate to a semiconductor circuit having a gm-C filter embedded therein, and more particularly, to a method of calibrating a frequency of the gm-C filter, by which a change in the frequency characteristics of the gm-C filter due to a process distribution as a result of semiconductor manufacturing process may be compensated for, and devices that may perform such a calibration method.
2. Description of the Related Art
The radio frequency (RF) front end of a receiver of a wireless communication device includes an analog filter capable of selecting a desired frequency from a received signal. Examples of the analog filter may include a switched capacitor filter (SCF), a MOSFET filter, a filter having an operational transconductance amplifier (OTA) structure, and the like. The filter having an OTA structure (which is also called as an OTA filter) is usually used to obtain filter characteristics from a frequency band of several tens of MHz.
The gm-C filter using transconductance gm is the most frequently used as the OTA filter. The gm-C filter is widely used for restoration of a received signal and anti-aliasing of a transmission signal in communication equipment. The gm-C filter includes a transconductor and a capacitor.
Transconductance gm of the transconductor and capacitance C of the capacitor in the gm-C filter are important factors in determining a cut-off frequency of the gm-C filter. The cut-off frequency of the gm-C filter is proportional to the transconductance and inversely proportional to the capacitance. To realize a gm-C filter having a high cut-off frequency capacitance may be reduced.